MHT CET 202622 AprilEvening Shift
- Exam
- MHT CET
- Year
- 2026
- Date
- 22 April
- Shift
- Evening Shift
- Subject
- Biology
- Chapter
- Molecular Basis of Inheritance
MHT CET 2026 · 22 April · Evening Shift · Biology · Molecular Basis of Inheritance
Which one of the following experiments by Griffith with...
Which one of the following experiments by Griffith with Streptococcus pneumoniae, resulted in the death of mice due to pneumonia?
Options
- AMice injected only with heat killed S strain.
- BMice injected with live R strain and heat killed S strain.
- CMice injected with heat killed R as well as S strains.
- DMice injected only with heat killed R strain.
Correct answer
B. Mice injected with live R strain and heat killed S strain.
Step-by-step solution
Frederick Griffith conducted a series of experiments with Streptococcus pneumoniae to demonstrate bacterial transformation.
When mice were injected with the live S strain (virulent), they died from pneumonia.
When injected with the live R strain (non-virulent), they survived.
When injected with the heat-killed S strain, they survived.
When injected with a mixture of live R strain and heat-killed S strain, the mice died. This occurred because some transforming principle from the heat-killed S strain enabled the live R strain to synthesize a smooth polysaccharide coat and become virulent.
Therefore, the injection of live R strain and heat-killed S strain resulted in the death of the mice.
Answer: Mice injected with live R strain and heat killed S strain.
When mice were injected with the live S strain (virulent), they died from pneumonia.
When injected with the live R strain (non-virulent), they survived.
When injected with the heat-killed S strain, they survived.
When injected with a mixture of live R strain and heat-killed S strain, the mice died. This occurred because some transforming principle from the heat-killed S strain enabled the live R strain to synthesize a smooth polysaccharide coat and become virulent.
Therefore, the injection of live R strain and heat-killed S strain resulted in the death of the mice.
Answer: Mice injected with live R strain and heat killed S strain.